When a stimulation electrode lead has been implanted and connected to a electrotherapy device, for example to a pacemaker or defibrillator, the electrical stimulation pulses supplied by the pacemaker or defibrillator are delivered, for example, to one of the chambers of the heart. Said chamber is usually the right ventricle, since stimulation electrode leads are usually inserted via the vena cava superior and the right atrium of the heart into the right ventricle. Many patients can be helped by stimulating just the right ventricle.
Dual-chamber pacemakers are also known that co-operate not only with electrodes in the right ventricle, but for which electrodes are also provided in the right atrium, so that both the right atrium and the right ventricle can be stimulated. In this way it is also possible to help those patients who lack natural synchronization of the right atrium and right ventricle. In a healthy person, the right atrium firstly contracts after being stimulated by the sinus node. After a certain time delay, the right ventricle contracts as a result of atrioventricular conduction. The heart functions optimally when this atrioventricular conduction time is physiologically well adjusted.
It is now known also that not only the right atrium and right ventricle of a heart can be stimulated, but also the left ventricle. This is particularly interesting for patients who suffer from congested heart failure (CHF). One problem associated with the left ventricle stimulation desired in such cases is that it is not easy to implant an electrode lead assigned to the left ventricle. One known option is to insert an electrode lead for the left ventricle through the vena cava superior and the right atrium into the coronary sinus and to place electrodes in the coronary sinus or in a lateral vein branching off it. Due to the fact that the latter blood vessels are very limited in diameter, the constructional requirements for an appropriate electrode lead are especially high. Firstly, it is essential, of course, that the electrode lead does not restrict the flow of blood through these blood vessels to any incompatible extent. Secondly, there is always the problem of ensuring that the electrode lead is suitably fixated in these blood vessels. Secure fixation of the electrode lead is also important, because ideal settings for a pacemaker must always be found for a given stimulation site, and such adjustment cannot be repeated as frequently as desired.
Known solutions for coronary sinus electrodes (comprising electrode leads with stimulation electrodes for placement in the coronary sinus or in a lateral vein branching off it) are dissatisfying in various respects, so there is still a need for a coronary sinus electrode that avoids the respective drawbacks of the known prior art.